In particular Go is shaped by the experience of needing to run high-performance servers at a company with thousands of engineers; it was designed to address a lot of the problems with running C++ or Python in that environment.
Swift came from Apple, and was designed to address a lot of the problems with writing mobile apps in Objective-C.
Where have you heard/read the part about Python? Not saying you're wrong, just haven't heard of it. I had heard about the C++ part. I know of some general issues (e.g. static typing, perf), of course, but interested to know which ones Google had (with Python).
Edit: The issues I've read about with C++ at Google (in Rob Pike's article) were, IIRC, C++'s complexity and long build times, even with distributed builds.
It seems more like a compiler/language developer's idea of what a good modern language should be.
Swift was designed for writing apps on the mac platforms, primarily on iOS, and although somewhat debatable as a replacement for Objective-C due to it's quirks. If you want proof of that, just read between the lines in the original documentation.
Not to mention, many of the features that were called out originally are direct responses to issues with Objective-C: Optionals, Typed containers, Generics, modules, real first class functions instead of just blocks, final classes, let, etc.
Those things were obviously requirements for roles it should fulfill.
But no things in its design hold it back from being a modern language that's even more expressive and fast than Go. Except some concurrency love perhaps.